Stephen S. Tucker

While two-photon fluorescence microscopy is a powerful platform for the study of functional dynamics in living cells and tissues, the bulk motion inherent to these applications causes distortions. We have designed a motion tracking module based on spectral domain optical coherence tomography which compliments a laser scanning two-photon microscope with real-time corrective feedback. The module can be added to fluorescent imaging microscopes using a single dichroic and without additional contrast agents. We demonstrate that the system can track lateral displacements as large as 10 μm at 5 Hz with latency under 14 ms and propose a scheme to extend the system to 3D correction with the addition of a remote focusing module. We also propose several ways to improve the module’s performance by reducing the feedback latency. We anticipate that this design can be adapted to other imaging modalities, enabling the study of samples subject to motion artifacts at higher resolution.

Functional near-infrared spectroscopy (fNIRS) is a family of noninvasive neuroimaging techniques that estimate concentrations of oxygenated and deoxygenated hemoglobin near the surface of the brain and thus infer relative changes in neural activation.¹ There are various technical approaches to NIRS measurements, most prominently the continuous-wave, frequency domain, and time-domain techniques. Each approach provides unique benefits, utilizes different instrumentation, and yields different raw data.^1,2